参考fname汽车理论

m2f+m2r+m2c=m2f+m2r+m2c= =mr2= a2+m2ry 2 y2my2r2m 2 yr2andpitchvibration"j" simplifyto nemodel4doms：2wheels,sprungmassdistributionr2悬挂质量分配系数：ee＝1connectionmass联系质量m2cTheverticalmovementofm2fandareindependent.Two domsdoms：onewheelDualmassvibration mur

mufSinglemassvibrationff<5Hzdeflectionoftyreissmall(ft:wheelnaturalfrequency车轮固有频率,ft10~15HZSinglemassvibrationsys. VibrationofSingleMasssecond-orderequationwithconstantC(z-q)+K(z-q)= assume:assume:2n=Cmw20=2m2w0systemnaturalcircularfrequencyf=w0=K0m2ratio阻尼比，zn=w0 m2K00

2z= belongtosmall\z=Ae-

w

-n2t+a0wr:systemnaturalfrequencywith0有阻尼固有频率,w=w2 vibrationscopeattenuationaccording e-nt振幅按e-nt衰减AttenuationAttenuationvibration衰减振动曲线AttenuationAttenuationvibrationinfluencedbywrwr=w2-n2＝w00z›wr z＝1wr＝0bigdampnovibration大阻尼时系统不振动z»0.25w0-wrw»3％r00有阻尼后振动频率变化不大AttenuationvibrationinfluencedbydA1 d=A1

Ae-

=

=e1-z2 Ae-n(t1+T2Measuredξby Measuredξby0nT= = 011+4p2/ln2(dfix

wr=1-z

w1- 1- (x›dFourierFouriertransformationf(t)=differentiationFdnf(t)n=(jw)F(w)n3.Frequencyresponsecharacteristicsofsinglemass+w20 =+w0 fiz(f时域z(t)3.Frequency3.Frequencyresponsecharacteristicsofsinglemass differential 对运动微分方程(jw)2z(w)+2n(jw)1z(w)+w2z(w)=2n(jw)1q(w)+w2q(w) -w2+j2nwz(w)=w2+j2nw z(w) w2+q(w)=(w2 0w2)+-0f(t)=dnf(t)F =(jw)nF(w)(dt)n 3.Frequency3.Frequencyresponsecharacteristicsofsinglemassinput输入q(t) 0(w2-w2)+0w2+=z(w)q(w)0(w2-w2)2+(2nw)0(w2)2+=3.Frequency3.Frequencyresponsecharacteristicsofsinglemass0w00

= 1+2

z(w)

2+wq(w) w

)+

-w2)+0z(w)0q(w)

1+(1-l2)2+l)2

z(w)

(w2)2+00(w2-w2)2+00powerpowerspectrumofscopefrequencycharacteristics•powerspectrumof输出的功率谱幅频特性2•ysisysisofscopefrequencyz(w)q(w)

1+(1-l2)2+l)20111012λ=ω/ω=1+(1-l2)2+l2ysisofscopefrequency(LF0z»dynamiccharacteristisysisysisofscopefrequency5l<x=

w0010111012λ=ω/ωz(w) (1-l2)2+1+x›，peakvaluez(w)ysisysisofscopefrequency高频区：l>Zx

z(w)0111012λ=ω/ω=1+(1-l2)2+l2=wq(w)

z(w)

z(w)=wq(w) q(w)=q(w)

z(w)q(w)

z(w)q(w)f(t)=F fnnn=(jw)F4.Response4.Responsetoroadsurfacerandominputofsinglemassndn4.Response4.Responsetoroadsurfacerandominputofsinglemass(1)(1)G(f)=G(f2q(2)G(f)fd2w)G(fqF2(3)G(f)= G(f dGq2GG(f)q(w)G(f)=wq2z(w)q(w)2z(w)q(w)G(fqG(f)G(f)=ww2G(fqG(f)G(f)2z(w)q(w)w4G(fq\G(f)=w2G(fqqG(f)=w4G(fqqG(f)=w2G(fqqGG(fq=q=1u1uG(n)q1uG(nq0nn)0G(fG(n2q001f=n=u\G(fq=G(n)n2q00f(f)=(2pf)2G(n (f)=G(n)n2u(2p)4 (f)=G(n)n2u(2p21f=G(n)n2u(2p G(f)=G(n)n2u(2p G(f)=G(nw (f)=G(n)n2u (f)=w2G(fq(f)=w4G(fqfG(f)=w2G(f 4.Response4.Responsetoroadsurfacerandominputofsinglemass

424G(f)=w22

2

2

f4.Response4.ResponsetoroadsurfacerandominputofsinglemassG(f)=w2

G(f)

G(nu(p)

f)

G(n f)

f)

G(nuw) Gq(fGq(f)white

w z(w)z(w

similargraph

z(w)q(w)

1+(1-l2)2+pointof

G(f

w1+

sw1+

flwfl-mainmeasure主要措施flflw0=2p

=2f0=1.1~1.5zcar），f01.5~2ztruck、crosscountry xneed:w0flm2

Km2andneed:x›m2\m1flm24.Response4.ResponsetoroadsurfacerandominputofsinglemassFd==z/g=1 4.Response4.ResponsetoroadsurfacerandominputofsinglemassAffd(w)=z(w)-q(w)=z(w)q(w) q(w) 1+2

1(1-l2+2 f(w) q(w)

(1-l2)2+ Gfd

(f)

fd(w)q(w)

Gq(f)

fd(w)

Gq(f (f)

fd(w)

G(f)=

fd(w)

G(f

wq(w) Gq(f)——whitenoisef(w l2 dd

1

w(1-l2)2+dw0 ›fdd

w

x› G(f)=wfdG(f)=wfd(w)q(w)G(fx›,

w0 ›,fddx›,fdddynamicdeflectionstatic

d 1fd

m2 wK0 wK0f=m2g

static \fd

note:Originofznote:Originofzisonstaticequilibriumiffd=fdneed:fd<fd为KC，车身的垂直位移为z，输入的路面不平度函数为q，路2m，路面不平度系数为输入功率谱输入功率谱: (f)q1uGq(n )n- n=3